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biological molecules > Water > Flashcards

Water Flashcards

1
Q

what elements make water

A

one atom of oxygen combines with two atoms of hydrogen by covalent bonds to form a water molecule

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2
Q

why is water a polar molecule

A

-the oxygen and hydrogen atoms combine by sharing electrons through covalent bonding.

However,the electrons are shared unequally between the oxygen and hydrogen atoms ,the electrons are more strongly attracted to the oxygen as it is more lectronegative than hydrogen thus creating a weak negatively charged region on the oxygen and a weak positively charged region around the hydrogen atoms

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3
Q

what is a dipole

A

the separation of charge due to the electrons in covalent bonds being shared unequally

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4
Q

why are the electron in a water molecule shared unequally

A

the oxygen atom is more electronegative than the hydrogen atoms so it attracts the electrons more strongly ,pulling them closer to itself ,resulting in a weakly negative region on the oxgen atoms and weakly positive region on the hydrogen atoms

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5
Q

how do hydrogen bonds form

A

the slightly negative oxygen atom is attracted to the slightly positive hydrogen atom of an adjacent water molecule

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6
Q

why is water polar

A

It has one end that has a slight negative charge and one that has a slight positive charge

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7
Q

what makes a molecule polar

A

has one end that is slightly negatively charged and one that is slightly positively charged

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8
Q

what shape is water

A

bent/non-linear

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9
Q

what is the bond angle in water

A

104.5

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10
Q

how many lone pairs does water have

A

2

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11
Q

how many bonding pairs does water have

A

2,oxygen forms one covalent bond with each hydrogen atom

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12
Q

between which elements can hydrogen bonding occur

A

occurs when a hydrogen atom is attached directly to either:
-Oxygen
-Nitrogen
-Fluorine

also oxygen,fluorine and nitrogen must have available lone pairs for hydrogen bonds to form

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13
Q

what are the properties of water that allow it to have essential functions

A

-polarity
- many hydrogen bonds occuring between water molecules

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14
Q

is it true than hydrogen bonds are strong

A

no,hydrogen bonds are weak,they form a strong structure only because there are present in large numbers,individually they are weak

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15
Q

State the properties of water

A

-relatively high specific heat capacity
-relatively high latent heat of evaporation
-ice is less dense than liquid water
-high surface tension
-cohesion, adhesion
-polarity
-hydrogen bonding
-acts as a reagent in reactions

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16
Q

what is the specific heat capacity of water

A

4200J/kg/oC

17
Q

what does it mean that water has a high specific heat capacity

A

it means that large amount of heat energy is required to raise the temperature of water

18
Q

Describe the role of water as a coolant and how it is useful

A

There are many hydrogen bonds that form between water molecules ,meaning that a large amount of energy is required to overcome them .This causes water to have high latent heat of evaporation ,meaning that large amount of energy is required to turn water into vapour, so when water evaporates from the skin via evaporation ,we lose a great amount of heat energy, resulting in what we refer to as the cooling effects

18
Q

what is the definition for specific heat capacity

A

the amount of thermal energy required to raise the temperature of 1kg of a substance by 1 oC

19
Q

Describe the role of water as a transport medium and how it is helpful for cells.

A

Water molecules have strong cohesion. This means that when water is transported through the body/stem, molecules stick together. This property of water allows water to flow in a continuous column, which is very important for transporting substances in many organisms.
Water also has adhesive properties, meaning that water molecules are attracted to and stick to other polar molecules.

Cohesion is an important property of water that helps to support life. For example, plants use the cohesive and adhesive properties of water in the transport of water up their stem and through the xylem in the transpiration stream .

It also contributes to the function of the cardiovascular system in animals by helping blood ( as blood consists of mostly water )to flow through narrow vessels.

Cohesion allows water to form droplets and to flow as a liquid rather than breaking up into separate molecules.

19
Q

Describe the role of water as a solvent and how that is useful for eukaryotes and prokaryotes

A

water is known as an universal solvent,

the polarity of water enables it to bind to polar molecules and charged ionic compounds, allowing them to dissolve; such compounds are known as hydrophilic.

explanation:

The weakly positively charged hydrogen is attracted to the negative ions, while the weakly negatively charged oxygen is attracted to positive ions.
Each ion is surrounded by water, allowing the compound to dissolve.

This is useful as the cytosol in eukaryotic and prokaryotic cells consists mainly of water. This means that hydrophilic substances like glucose and important ions like Ca2+ and K+ ions can dissolve in the cell’s cytosol and be easily transported from the site where they are made to the site where they are needed, allowing chemical reactions to occur in the cell.

Water acts at the medium for chemical reactions and transports dissolved compounds into and out of cells

20
Q

Describe the role of water as a habitat and how it’s useful for organisms

Describe the ice less dense than liquid water theory.

A

ICE IS LESS DENSE THAN LIQUID WATER
One of the properties that makes water a good habitat is that ice floats over liquid water.
This is because each water molecule forms four hydrogen bonds, connecting them in a lattice shape. The lattice holds the water molecules further apart/This increases the space between water molecules and thus makes ice less dense than liquid water.
This means that ice floats over liquid water; therefore, in the colder months, ice forms an insulating layer so that the water beneath doesn’t freeze, allowing aquatic organisms to survive.

THE ICE ITSELF ALSO PROVIDES A HABITAT FOR ORGANISMS LIKE POLAR BEARS

21
Q

water as a good habitat

-describe the role in term of water having high surface tension

A

Water is a good habitat because of its tendency to stick to other water molecules, also known as cohesion.The cohesive properties of water mean that water molecules on the top layer of water are more attracted to each other than they are to air.This results in high surface tension and causes a thin ‘skin’to form on the top layer of water which is difficult to break through.This skin acts as a habitat for insects like pond skaters

22
Q

water as a good habitat-talk about water having a high specific heat capacity

A

Water molecules form many hydrogen bonds with adjacent water molecules. These hydrogen bonds within water can absorb large amounts of energy as a large amount of energy is required to break or form them. This results in water having a relatively high specific heat capacity,
which means that a lot of thermal energy is required to rais the temperature of the water. Therefore water is able to stay fairly resistant to changes in temperature, making it a stable habitat for organisms to live.

23
Q

water as a coolant-talk about the cooling effect

A

water contains many hydrogen bonds,it requires a lot of energy to overcome them. This results in water having a relatively high latent heat of evaporation, meaning that large amount of energy is required to convert liquid water into a gas. Therefore when organisms sweat and water evaporates ,it causes organisms to lose a great amount of heat energy with it,providing for what we call a ‘‘cooling effect’ in living organism.-prevents us from heatstroke

This is why we feel cooler when we sweat, since the evaporation of water from our skin’s surface takes a lot of heat energy with it.

24
Q

talk about water maintaining optimal temperature in cells

A

-water having high specific heat capacity as result of its many hydrogen bonds mean that it can absorb large amount of heat energy while staying relatively resistant to changes in temperature

This is vital for maintaining optimal temperatures in cellular environmenmts for enzyme activity, allowing important chemical reactions to occur

24
Q

water as incompressible

A

Water is incompressible. Water is (for the most part) incompressible, meaning it cannot be squashed under normal conditions. For example, if you fill a balloon with water and try to squash it completely, the balloon would burst rather than yield under your pressure. This is due to the many hydrogen bonds between the water molecules.

24
Q

other relevant properties of water

A

-transparent
-can act as a reagent
-high boiling temp

24
Q

How do ca2+ ions dissolve in water

A

Ca2+ ions have a positive charge. Water’s polarity means that the slightly negatively charged oxygen atom of the molecule is attracted to the positively charged ions and surrounds them,allowing them to dissolve.

25
Q

what is cohesion

A

the attraction between molecules of the same type

26
Q

what is adhesion

A

the attraction of molecules of different types

biological molecules (14 decks)

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